The invention relates to a corona ignition device of the type generally known from DE 10 2012 108 251 A1.
The insulator of such a corona ignition device protrudes with an end portion out of the housing of the corona ignition device. For the shape of the insulator, in particular the end portion thereof, a multiplicity of variants is known. Thus, for example, EP 1 869 739 B1 discloses a corona ignition device, the isolator of which has a cylindrical end portion; US 2010/0175655 A1 discloses a corona ignition device, the insulator of which has an end portion in the form of a truncated cone having an acute cone angle; EP 1 875 571 B1 discloses a corona ignition device, the insulator of which has an end portion in the form of a truncated cone having an obtuse cone angle, and US 2013/0003251 A1 discloses a corona ignition device, the insulator of which has a conical recess in which a plurality of ignition tips of the center electrode are arranged.
The influence of the insulator on the function and the service life of a corona ignition device is complex. Deposits of fuel residues as well as cracks, which can occur during the operation due to thermal stress or temperature shocks, can negatively affect the function of a corona ignition device. Moreover, the insulator, due to its thermal coupling to the center electrode inserted therein, also influences the temperature of ignition tips of the center electrode and thus indirectly also influences the ignition behaviour of the ignition tips and the wear thereon.